The invention relates to an apparatus and method for transferring articles into and out of cases using continuous motion, and particularly, where the continuous motion is basically circular at higher transfer speeds with a small footprint.
In the art of case packing, large numbers of articles must be grouped and packaged rapidly by an apparatus that will function dependably without damage to the articles processed. When unpacking articles from cases, the articles are already grouped in a pattern in the case reducing some of the problems of article pickup. Case packing apparatus has been generally categorized as either intermittent case packing or continuous case packing. In intermittent case packing the article flow and/or case flow is interrupted during article pickup and/or release. Most recently, attention has been directed to continuous case packing in order to increase production. However, the continuous case packing has brought increased problems with handling the processed articles without breakage, damage, or interruption.
In the continuous case packing apparatus, articles are grouped together in successive slugs at a pickup position. The slugs are typically picked up at the pickup position by article grippers carried by an orbital handling machine rotating about two vertical axes. The slugs are transferred to a case loading position where the grippers release the slug of articles into a case. The articles can be released either simultaneously or sequentially as the case is conveyed beneath the slug of articles. Apparatus of this type may be either of the xe2x80x9cdrop packerxe2x80x9d type or xe2x80x9cplacement packer type.xe2x80x9d In the drop packer type, the articles are allowed to drop at least a small distance into the case after release. In the placement packer type, the drop, if any, is minimal and the articles are essentially placed gently onto the bottom of the case.
Continuous motion machines rotating about a single horizontal axis are shown in U.S. Pat. Nos. 5,375,395, 5,257,888, and 5,313,764 using articulating arms and pickup heads. A set of article grippers is carried on the ends of the articulating arms. However, during the angular descent from the pickup position to the case packing position, both horizontal and vertical accelerations are typically encountered by the articles which are gripped only at their tops or necks. Intermittent circular machines rotating about a single vertical axis are shown in U.S. Pat. Nos. 3,780,492 and 2,807,125.
Various other case packers, generally of the continuous motion type, using a vertical orbital conveyor are shown in U.S. Pat. Nos. 5,212,930; 4,541,524; and 4,294,057. The first patent shows depositing the articles sequentially and individually, rather than as a group or slug, into partitioned cases without positively gripping the articles. The latter two patents use gripper devices to grip and place the articles. U. S. Pat. No. 4,457,121 discloses a continuous motion bottle packer wherein a plurality of grids are mounted individually on spokes of a vertical wheel so that each grid moves through an article infeed position where groups of articles are fed into the grid without interrupting the forward speed. Angular and horizontal accelerations of the articles and their contents are encountered due to the rotary wheel motion during the transfer which may be detrimental to the article and/or contents.
Continuous case packers are also known in which a horizontal rotary carousel is used to move vertically reciprocating gripper sets in a horizontal plane about two vertical axes. The reciprocating gripper sets pick up a slug of articles at one position and transfer the slug of articles to a second position where the gripper set is lowered to deposit the articles into a case. Typically the pickup and release stations are on opposite sides of the carousel, requiring parallel conveyors on each side. However, the disposition of the rotary carousel in a horizontal plane requires an inconvenient floor lay-out which also occupies a large amount of floor space. The parallel conveyor arrangements needed for the infeed and outfeed of articles adds to the floor space problem. The path of the gripper sets between the slug pickup position and the case packing position is also typically curved producing angular and acceleration forces on the articles. The curved article transfer path intersects the path of the conveyed case only for a brief interval making timing a factor. In various of the rotary carousel types, it is known to deposit the articles by lowering the articles, already gripped by the gripper set, through resilient fingers that guide the articles into partitioned cases.
Case packers, generally of the intermittent type, are shown in U.S. Pat. Nos. 3,553,932 and 3,505,787 which also disclose using combinations of a lifting head having suction cups and bottle grids having pockets for picking up containers and depositing them into cases. The containers and the cases are conveyed on parallel conveyors rather than in-line conveyors, and the transfer from the pickup position to the case loading position is lateral, or transverse, to the flow of containers and cases. U.S. Pat. No. 2,277,688 discloses another case packer using an arrangement of a gripper set and a bottle guide set to package the containers into a case. These type of case packers are generally non-continuous as compared to the continuous motion in-line transfer case packers described above where neither the flow of articles nor the flow of the cases is interrupted during operation of the packer.
Accordingly, an object of the invention is to provide an improved continuous case packing and depacking apparatus having a characteristic circular motion.
Another object of the invention is to provide a continuous motion apparatus and method which moves in a circular motion to provide high speeds of operation.
Another object of the invention is to provide a continuous, circular motion case packing or depacking apparatus and method which rotates about a single axis to provide a small footprint and high speed operation.
Another object of the invention is to provide a continuous, circular motion case packing apparatus and method in which slugs or groups of articles are picked up and transferred to a release station where the motion of the pickup heads is converted to a substantially straight-line motion along a pickup section during which time the articles are picked up.
Still another object of the invention is to provide a continuous, circular motion case packing or depacking apparatus and method wherein the articles are either picked up or released over an arcuate section of a conveyor disposed below the path of pickup heads rotating along a common arc.
Yet another object of the invention is to provide a continuous motion apparatus and method in which a revolving turret moves a plurality of transfer arms in a circular path about a single vertical axis as reciprocating article pickup heads and/or grid heads, carried by the transfer arms, pickup and release the articles wherein either the pick up or release occurs over an arcuate conveyor section disposed below the pickup heads moving in a circular motion for high speed, reliable operation.
The above objectives are accomplished according to the present invention by providing apparatus and method for transferring articles from a pickup station to a release station basically in a continuous circular motion. The apparatus includes a rotating turret which continuously rotates about a substantially vertical axis for continuously transferring the articles. A plurality of reciprocating article pickup heads are carried by the rotating turret for continuously and successively picking up groups of the articles at the pickup station and releasing the articles at the release station. A conveyor is provided having an arcuate conveyor section disposed generally below a congruent path of the pickup heads over which the heads are continuously rotated. Advantageously, one of the pickup and release stations is located along the arcuate section of the conveyor.
In a case packing embodiment of the invention, the turret rotates the pickup heads in a closed curvilinear path around the vertical axis which includes a circular section and a generally linear pickup section along which the circular motion of the pickup heads is converted to a substantially linear motion to pick up the articles while the turret rotates. For this purpose, the apparatus may include a motion converter operatively associated with the pickup heads for causing the pickup heads to move generally in a straight-line motion along the pickup section, a distance which corresponds generally to a predetermined arc of turret rotation. In one illustrated embodiment of the invention, the motion converter includes support frames carried by transfer arms, and the pickup heads are slidably carried by the support frames whereby the pickup heads swivel and translate to maintain a straight-line motion along the pickup section as the turret rotates. The motion converter may include connector mechanisms associated with the rotating turret and the pickup heads for imparting the motion. Advantageously, the connector mechanisms may include vertical cam shafts and linkage arrangements connected between the cam shafts and pickup heads. The linkage arrangements are slidably carried by the vertical cam shafts to slide up and down as the pickup heads reciprocate during pick up and release of the articles. Cam followers may be connected to the linkage arrangements, with at least one cam assembled to a fixed center column which the cam followers follow as the turret rotates to impart the straight-line motion to the pickup heads.
The pickup station may be a station where articles are picked up for packing into cases, or a station where empty articles are removed from cases. Likewise, the release station may be a case packing station, or a station where empty articles are released on a conveyor to be conveyed away. When the release station is a case packing station, it may be located along the arcuate conveyor section, and the conveyor conveys indexed cases to the arcuate conveyor section for receiving the released articles in synchronization with the rotating turret. In this case, a plurality of grid heads may be advantageously carried below the pickup heads. The grid heads may have guides in the form of pivoting grid fingers arranged in a grid corresponding to an array of the articles to be picked up. The grid fingers define grid chutes having upper and lower ends for receiving the articles. The pickup heads have gripper elements arranged in a pattern corresponding to the pattern of grid chutes for gripping the articles.
Preferably, a vertical motion mechanism is provided which controls the operative positions of the pickup and/or grid heads. The mechanism may include two cams encircling and supported by the stationary center column affixed inside the rotating turret. The pickup and grid heads may be slidably carried on vertical transfer arms carried by the turret. A cam roller associated with the pickup and grid heads rides on a respective cam to control the vertical position of the heads. A pickup head actuator mechanism may be provided for actuating the gripper elements to selectively grip and release the articles. In one form of the invention, the pickup head actuator mechanism may include gripper actuators carried by the pickup heads having movement between a closed position wherein the articles are gripped, and an open position wherein the articles are released by the gripper elements. An operator controls the movement of the gripper actuators between the open and closed position. An engagement member may be carried by the stationary column and positioned at the release station. The operator is arranged to strike the engagement member at the release station whereby the gripper actuators are moved to the open position for releasing the articles. In the case packing embodiment of the invention, the grid heads provide guides so that the articles are reliably inserted into pockets of the partitioned cases. For this reason, the motion of the grid heads may also be controlled by the motion converter in unison with the pickup heads whereby their circular motion is converted into a straight-line motion for article pick up.
In accordance with the method of the invention, a method is provided for continuously transferring articles between a pickup station and a release station which comprises continuously conveying the articles to a pickup station; and continuously picking the articles up at the pickup station using pickup heads rotating about a single vertical axis in a closed cyclic path. Basically, as applied to case packing, the invention contemplates using reciprocating pickup heads carried on a rotating turret, and converting the circular motion of the pickup heads to a straight-line motion over a predetermined arc of the turret along which the articles are picked up. The method advantageously includes providing an arcuate conveyor section, and carrying out one of the article pick up and release steps while the pickup heads are moving in a common path over the arcuate conveyor section. The method includes, in one embodiment, conveying the cases to the arcuate conveyor section and picking up empty articles from the cases along the arcuate conveyor section for depacking the cases. In a second embodiment, the invention includes picking up articles delivered by an article infeed conveyor, and releasing the articles over the arcuate conveyor section into empty cases at a case packing station.